Socio-economic status is inversely related to bed net use in Gabon

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Influence of small additions of MeC on properties of binderless tungsten carbide

The aim of this research is to investigate the effect of small MeC additions to ultrafine WC. The studied MeC added are VC, Cr3C2, Mo2C, NbC, TaC, ZrC and TiC with quantities of 1 wt.% (between 1.1 and 3.1 Vol.%). Mixtures were milled, cold isostatic pressed and sintered using a sinterHIP furnace at 1900 °C. The results showed that except for TiC addition no residues of the MeC additions could be detected by XRD. EDS analysis showed only homogenously distributed Me and no pure MeC phase could be found, hinting the dissolution of Me atoms within Tungsten Carbide (WC or W2C). However, in case of the addition of TiC a second phase consisting of W and Ti and the structure of (Ti, W)C2 was detected by EDS and XRD

Rate controlled sintering of binderless tungsten carbide

Prevention of the typical densification peaks of conventional constant-heating-rate sintering (CHR) by real-time densification rate control can provide better materials with less microstructural heterogeneities, residual stresses and abnormal grain growth inter alia. FAST/SPS spark plasma sintering systems are able to realize this control by a smooth adjustment of heating rate and applied force, making this technique ideal to investigate the effect of rate controlled sintering (RCS). Within this work nanoscaled binderless tungsten carbide samples were produced by conventional as well as densification rate controlled sintering realized by adjusting the applied force or heating rate during the respective sintering cycle. Especially by controlling the heating rate, the resulting samples showed an increase of density associated to around 250 HV10 higher hardness compared to the conventionally FAST/SPS sintered samples. Microstructural analysis revealed a slightly smaller grain size

Low-temperature spark plasma sintering of pure nano wc powder

For the first time we have demonstrated the densification of high-purity nanostructured (davg about 60 nm) tungsten carbide by High Pressure Spark Plasma Sintering (HPSPS) in the unusually low temperature range of 1200°C-1400°C. The high-pressure sintering (i.e., 300 MPa) produced dense material at a temperature as low as 1400°C. In comparison with more conventional sintering techniques, such as SPS (80 MPa) or hot isostatic pressing, HPSPS lowered the temperature required for full densification by 400°C-500°C. High Pressure Spark Plasma Sintering, even in absence of any sintering aid or grain growth inhibitor, retained a very fine microstructure resulting in a significant improvement in both hardness (2721 HV10) and fracture toughness (7.2 MPa m1/2)